Process for producing polyurethane

ABSTRACT

A catalyst for producing a polyurethane, comprising a dialkylaminoalkyl alcohol represented by the formula (I):  
     R 1 R 2 N—X—OH  (I)  
     wherein each of R 1  and R 2  is independently an alkyl group having 1 to 4 carbon atoms; and X is a branched alkylene group having 4 to 8 carbon atoms; a process for producing a polyurethane, comprising reacting a polyol component with an isocyanate component in the presence of the above-mentioned catalyst for producing a polyurethane; and a process for producing a polyurethane foam, comprising reacting a polyol component with an isocyanate component in the presence of the above-mentioned catalyst for producing a polyurethane, and a compound having a primary amino group and a tertiary amino group in its molecule, and a blowing agent. The polyurethane can be used as heat insulating materials for construction materials, electric refrigerators, refrigerated warehouses, baths and the like, interior materials for automobiles, furnishings, cushioning materials for beddings, various sealing materials and the like.

TECHNICAL FIELD

[0001] The present invention relates to a catalyst for producing apolyurethane, and a process for producing a polyurethane in which thecatalyst is used, such as a flexible, rigid or semi-rigid polyurethanefoam or a polyurethane elastomer. More specifically, the presentinvention relates to a process for producing a polyurethane such as apolyurethane foam which can be used as heat insulating materials forconstruction materials, electric refrigerators, refrigerated warehouses,baths and the like, interior materials for automobiles, furnishings,cushioning materials for beddings, various sealing materials and thelike, and a catalyst for producing a polyurethane used therefor.

BACKGROUND ART

[0002] As a catalyst used in the production of a polyurethane,N,N,N′,N′-tetramethylethylenediamine andN,N,N′,N′-tetramethylpropylenediamine have been widely used because oftheir appropriate catalytic activity and excellent moldability. However,there are serious defects in public health when the catalysts are usedsince the catalysts not only exhibit bad stimulative smells but alsogenerate eye rainbow (the state where a rainbow is observed) due to thevapor of the catalyst during the operation for the production.

[0003] In order to eliminate these defects, there has been proposed atertiary amine catalyst such as 1,4-diazabicyclo[2.2.2]octane orN,N,N′,N′-tetramethylhexamethylenediamine. The effects due to thecatalysts can be recognized to some extent. However, it could not yethave been said that the effects are sufficient. Also, since thesetertiary amine catalysts would not be incorporated into the polyurethanevia a chemical bond during the urethanation, there are some defects inthe catalysts such that there occur inconvenient results such as aso-called “vinyl-staining” which is caused by the discoloration of avinyl chloride resin sheet used as a substrate, and a so-called“fogging” meaning the fogging of window glass of an automobile due tothe catalyst vapor diffused from the polyurethane.

[0004] As an amine catalyst which is incorporated into the polyurethaneduring the urethanation, there has been proposed a tertiary aminecatalyst having in its molecule a hydroxyl group and an amino groupreactive with isocyanate group. When the tertiary amine catalyst isused, the problems in vinyl-staining and fogging are solved. However,the molecular structure of the polyurethane would be changed by theamine catalyst, so that there are some defects in heat resistance suchthat the strength is lowered especially when the polyurethane is exposedto an atmosphere having a high temperature for a long period of time,and that the polyurethane is colored.

[0005] On the other hand, a rigid polyurethane foam has been used asheat insulating materials for construction materials, electricrefrigerators, refrigerated warehouses, baths and pipes because of itsexcellent heat insulation.

[0006] When the polyurethane foam is used, for instance, as heatinsulating materials for house or building construction materials, thepolyurethane foam has been produced by mixing a component comprising apolyol as a main component with a component comprising a polyisocyanateas a main component, spraying the resulting mixture to a desired sitesuch as wall surface or ceiling in the construction site of a house orbuilding with a spray machine or the like to foam, and curing the foam.

[0007] When the polyurethane foam is formed in a manner as describedabove, peculiar strong odor based on the used tertiary amine catalystworsens the working environment. Moreover, since the unreacted tertiaryamine catalyst remains in the polyurethane foam even after molding,there are some problems in public health such as odor caused by therelease and dispersion of the tertiary amine catalyst from thepolyurethane foam. Recently, as a catalyst for producing a polyurethanewhich causes little problem in public health, there has been proposed atertiary amine catalyst having a hydroxyl group in its molecule for thepurpose of the avoidance of vinyl-staining and fogging (Japanese PatentLaid-Open Nos. Sho 62-115017 and Sho 61-252219).

[0008] When the tertiary amine catalyst having a hydroxyl group in itsmolecule is used in the production of the polyurethane foam, the problemregarding odor is eliminated. However, since the reactivity of thepolyol component with the isocyanate component used in the production ofthe polyurethane foam is low at low temperatures, a long period of timeis required for the production. Especially, when the polyurethane foamis formed by means of spraying, problems such as dripping would becaused. Also, there are some defects such that heat of the polyurethanefoam generated during the production is robbed off by the air, and thatthe reaction is less likely to proceed, so that the compressive strengthis lowered and its dimensional stability is lowered at low temperatures.

[0009] An object of the present invention is to provide a catalyst forproducing a polyurethane exhibiting little odor, and a process forproducing a polyurethane foam excellent in vinyl-staining resistance,fogging resistance and heat resistance, using the catalyst for producinga polyurethane.

[0010] Another object of the present invention is to provide a processcapable of rapidly producing a polyurethane foam excellent indimensional stability even under low-temperature surroundings with thegeneration of little odor based on the catalyst for producing apolyurethane.

[0011] These and other objects of the present invention will be apparentfrom the following description.

DISCLOSURE OF INVENTION

[0012] Specifically, the present invention relates to

[0013] (1) a catalyst for producing a polyurethane, comprising adialkylaminoalkyl alcohol (hereinafter referred to as “DAAA”)represented by the formula (I):

R¹R²N—X—OH  (I)

[0014] wherein each of R¹ and R² is independently an alkyl group having1 to 4 carbon atoms; and X is a branched alkylene group having 4 to 8carbon atoms;

[0015] (2) a process for producing a polyurethane, comprising reacting apolyol component with an isocyanate component in the presence of acatalyst for producing a polyurethane, comprising the DAAA; and

[0016] (3) a process for producing a polyurethane foam, comprisingreacting a polyol component with an isocyanate component in the presenceof a catalyst for producing a polyurethane, comprising the DAAA, and acompound having a primary amino group and a tertiary amino group in itsmolecule (hereinafter referred to as “FTA compound”) and a blowingagent.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a schematic explanatory view of a test piece of apolyurethane foam used in the determination of dimensional stability atlow temperatures.

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] The catalyst for producing a polyurethane, comprising a DAAArepresented by the formula (I) generates little odor, and has excellentcharacteristics of imparting vinyl-staining resistance, foggingresistance and heat resistance to the polyurethane obtained.

[0019] Incidentally, the term “comprising” includes two concepts: theone is a case where only the DAAA is used, and the other is a case wherethe other catalyst for producing a polyurethane is contained togetherwith the DAAA within a range which would not hinder the object of thepresent invention.

[0020] In the formula (I), each of R¹ and R² is independently an alkylgroup having 1 to 4 carbon atoms. It is preferable that each of R¹ andR² is methyl group from the viewpoint of catalytic activity.

[0021] X is a branched alkylene group having 4 to 8 carbon atoms. Amongthem, those having no branched chain at alpha and beta positions of thenitrogen atom are preferable from the viewpoint of catalytic activity.

[0022] As preferred concrete examples of the DAAA, there can be cited5-dimethylamino-3-methyl-1-pentanol, 4-dimethylamino-2-methyl-1-butanol,4-dimethylamino-2,2-dimethyl-1-butanol,5-dimethylamino-3,3-dimethyl-1-pentanol,6-dimethylamino-2-ethyl-1-hexanol, and the like. These can be used aloneor in admixture of at least two kinds. Among them,5-dimethylamino-3-methyl-1-pentanol is especially preferable, from itshigh yield in preparation, and its inexpensive preparation.

[0023] The DAAA can be readily prepared by reacting a correspondingbranched alkanediol with a dialkylamine.

[0024] Especially, 5-dimethylamino-3-methyl-1-pentanol can be preparedby reacting 3-methyl-1,5-pentanediol as a starting material withdimethylamine. However, a large amount ofbis(1,5-dimethylamino)-3-methylpentane in which dimethylamino groups arebonded to the two hydroxyl groups of 3-methyl-1,5-pentanediol is formedas a by-product of 5-dimethylamino-3-methyl-1-pentanol, thereby loweringits yield. However, when 5-hydroxy-3-methyl-1-pentanal which isindustrially readily available is used as a starting material,5-dimethylamino-3-methyl-1-pentanol can be prepared in a high yieldsince 5-dimethylamino-3-methyl-1-pentanol in which dimethylamino groupis bonded only to the aldehyde, can be selectively prepared by reactingthe aldehyde with dimethylamine.

[0025] The amount of the catalyst for producing a polyurethanecomprising DAAA cannot be absolutely determined because the amount ofthe catalyst varies depending upon the kind of the polyurethane. It isdesired that the amount of the catalyst for producing a polyurethane isusually at least 0.3 parts by weight, preferably at least 0.5 parts byweight based on 100 parts by weight of the polyol component which is astarting material of the polyurethane, from the viewpoint of increasingthe reactivity of the polyol component with the isocyanate component.Also, it is desired that the amount of the catalyst for producing apolyurethane is at most usually 10 parts by weight, preferably at most 8parts by weight based on 100 parts by weight of the polyol component,from the viewpoint of maintaining the strength of the polyurethane.Therefore, in view of the above circumstances, the desired amount of thecatalyst for producing a polyurethane is 0.3 to 10 parts by weight,preferably 0.5 to 8 parts by weight based on 100 parts by weight of thepolyol component.

[0026] The kind of the polyurethane to which the catalyst for producinga polyurethane comprising the DAAA is applicable is not limited tospecified ones. As the polyurethane, there can be cited flexible, rigidand semi-rigid polyurethane foams, polyurethane elastomers, and thelike, but the present invention is not limited only to those exemplifiedones. Among them, the flexible, rigid and semi-rigid polyurethane foamsare preferable.

[0027] In addition, when a polyurethane foam is produced for anotherpurpose of the present invention, it is preferable to use a catalyst forproducing a polyurethane comprising the DAAA and the FTA compound.

[0028] When the catalyst for producing a polyurethane comprising theDAAA and the FTA compound is used, little odor based on the catalystwould be generated during the production of a polyurethane foam.Moreover, there can be exhibited an excellent effect such that apolyurethane foam being excellent in dimensional stability can berapidly produced even in the low-temperature surroundings as in winterseason. The reason why the above excellent effect is exhibited would bepresumably based on the facts that the DAAA suppresses the odor of theFTA compound by using the DAAA together with the FTA compound, and thatthe reactivity is improved at low temperatures and the cross-linkingdensity is increased by the synergistic effects of the combined use ofthese compounds, so that the dimensional stability is improved at lowtemperatures.

[0029] As described above, when the catalyst for producing apolyurethane comprising the DAAA and the FTA compound is used, theseexcellent effects are exhibited. Therefore, even in low-temperaturesurroundings as in winter season, a rigid polyurethane foam can beproduced by directly spraying a mixture containing the catalyst to adesired site such as wall surface or ceiling in a construction site suchas house, building or the like with a spraying machine or the like tofoam, and curing the foam, and the formed rigid polyurethane foam can besuitably used as a heat insulating material for construction materialsand the like. Moreover, since the resulting polyurethane foam generateslittle odor based on the catalyst for producing a polyurethane, when thecatalyst is used for the production of a semi-rigid polyurethane foam,the obtained semi-rigid polyurethane foam can be suitably used, forinstance, for interior materials for automobiles such as headrests.

[0030] As representative examples of the FTA compound, there can becited a compound represented by the formula (II):

R³R⁴N—(CH₂)_(m)—A—(CH₂)_(n)—NH₂  (II)

[0031] wherein each of R³ and R⁴ is independently an alkyl group having1 to 4 carbon atoms, or may be bonded to each other to form a 3- to6-membered nitrogen atom-containing heterocyclic group; A is oxygen atomor a single bond, and when A is oxygen atom, each of m and n isindependently an integer of 2 to 6, and when A is a single bond, each ofm and n is an integer satisfying m+n=2 to 8.

[0032] As concrete examples of the FTA compound represented by theformula (II), there can be cited dialkylaminoalkylamines such as3-dimethylaminopropylamine, 3-diethylaminopropylamine,3-dipropylaminopropylamine, 4-dimethylaminobutylamine,6-dimethylaminohexylamine, 3-(2-dimethylaminoethoxy)propylamine,2-dibutylaminoethylamine and 8-dimethylaminooctylamine; heterocyclicaminoalkylamines such as 2-(1-aziridinyl)ethylamine,3-(1-pyrrolidinyl)-1-propylamine, N-(2-aminoethyl)piperazine,N-methyl-N′-(2-aminoethyl)piperazine, 1,4-bis(2-aminoethyl)piperazine,N-(3-aminopropyl)piperazine, N-methyl-N′-(3-aminopropyl)piperazine,1,4-bis(3-aminopropyl)piperazine, 2-(1-morpholino)ethylamine and3-(1-morpholino)propylamine; and the like. These can be used alone or inadmixture of at least two kinds. Among them, at least one compoundselected from the group consisting of 3-dimethylaminopropylamine,4-dimethylaminobutylamine, 6-dimethylaminohexylamine and3-(2-dimethylaminoethoxy)propylamine, especially3-dimethylaminopropylamine can be suitably used, from the viewpoint thatvery little odor is generated when used together with the DAAA.

[0033] The DAAA/FTA compound [weight ratio] is preferably 5/95 to 95/5,more preferably 10/90 to 80/20, from the viewpoint of preventing theodor and the viewpoint of improving the reactivity.

[0034] In addition, it is desired that the total amount of the DAAA andthe FTA compound is at least 0.5 parts by weight, preferably at least 1part by weight based on 100 parts by weight of the polyol component,from the viewpoint of increasing the reactivity of the polyol componentwith the isocyanate component and the viewpoint of improving thedimensional stability at low temperatures. Also, it is desired that thetotal amount of the DAAA and the FTA compound is at most 10 parts byweight, preferably at most 8 parts by weight based on 100 parts byweight of the polyol component, from the viewpoint of maintaining thestrength of the polyurethane foam. Therefore, in view of the abovecircumstances, it is desired that the total amount is 0.5 to 10 parts byweight, preferably 1 to 8 parts by weight based on 100 parts by weightof the polyol component.

[0035] The other catalyst for producing a polyurethane may be usedwithin a range which would not hinder the object of the presentinvention. It is preferable that the other catalyst for producing apolyurethane foam is one having a boiling point of at least 130° C. fromthe viewpoint of suppressing its evaporation or volatilization since itsinternal temperature becomes 100° to 130° C. or so during the productionof polyurethane foam.

[0036] As the other catalysts for producing a polyurethane, there can becited, for instance, tertiary amine catalysts such as1,4-diazabicyclo[2.2.2]octane, 2-methyl-1,4-diazabicyclo[2.2.2]octane,N-ethylmorpholine, N-(dimethylaminoethyl)morpholine,N,N,N′,N′-tetramethylpropylenediamine,N,N,N′,N′-tetramethylhexamethylenediamine,N,N′,N′-trimethylaminoethylpiperazine, N,N-dimethylcyclohexylamine,N,N-dimethylbenzylamine, N,N,N′,N″,N″-pentamethyldiethylenetriamine,bis(2-dimethylaminoethyl) ether, 1,8-diazabicyclo[5.4.0]undecene-7,N,N′,N″-tris(3-dimethylaminopropyl)hexahydro-s-triadine,6-dimethylamino-1-hexanol, N,N-dimethylethanolamine,N,N-dimethylaminoethoxyethanol and N,N-dimethylaminoethoxyethoxyethanol,derivatives thereof, salts thereof with an acid such as a carboxylicacid or carbonic acid; organometallic compounds represented by organotincompounds; and the like.

[0037] For the purpose of imparting anti-flaming property to apolyurethane foam, the catalyst can be used together with a catalyst forproducing a polyisocyanurate represented by a potassium salt such aspotassium acetate or potassium octylate, or a quaternary ammonium salt.

[0038] The amount of the other catalyst for producing a polyurethane andthe amount of the catalyst for producing a polyisocyanurate are notlimited to specified ones, and may be appropriately adjusted within arange which would not hinder the object of the present invention.

[0039] The polyurethane can be produced by reacting the polyol componentwith the isocyanate component in the presence of the catalyst forproducing a polyurethane comprising the DAAA. Among the polyurethanes,when a polyurethane foam is produced, a polyurethane foam can beproduced by reacting a polyol component with an isocyanate component inthe presence of the catalyst for producing a polyurethane comprising theDAAA, a blowing agent, and, as occasion demands, a surfactant.

[0040] The polyol component is not limited to specified ones, and may beany of those conventionally used ones during the production of apolyurethane.

[0041] As the polyol component, there can be cited polyester-polyols andpolyether-polyols.

[0042] The polyester-polyol can be prepared by a condensation reactionof a dicarboxylic acid with a polyhydric alcohol.

[0043] As the dicarboxylic acid used for the polyester-polyol, there canbe cited saturated aliphatic dicarboxylic acids such as glutaric acid,adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid;saturated alicyclic dicarboxylic acids such as cyclohexanedicarboxylicacid; aromatic dicarboxylic acids such as phthalic acid, terephthalicacid and isophthalic acid; unsaturated aliphatic dicarboxylic acids suchas maleic acid, fumaric acid and itaconic acid; halogen-containingdicarboxylic acids such as tetrabromophthalic acid; ester-formablederivatives thereof; acid anhydrides thereof; and the like. These can beused alone or in admixture of at least two kinds. Incidentally, thedicarboxylic acid may contain a polybasic acid having at least threefunctional groups, such as trimellitic acid or pyromellitic acid asdesired.

[0044] As the polyhydric alcohol constituting the polyester-polyol,there can be cited ethylene glycol, diethylene glycol, propylene glycol,1,4-butanediol, 1,5-pentanediol, methylpentanediol-1,6-hexanediol,trimethylolpropane, glycerol, pentaerythritol, diglycerol, dextrose,sorbitol, and the like. These can be used alone or in admixture of atleast two kinds.

[0045] As representative examples of the polyether-polyol, there can becited polyoxypropylene-polyols, polyoxytetramethylene glycols, mixturesthereof, and the like.

[0046] The polyoxypropylene-polyol can be prepared by a ring-openingaddition reaction of an alkylene oxide such as ethylene oxide, propyleneoxide, 1,2-butylene oxide, 1,3-butylene oxide or styrene oxide, using acompound having at least two active hydrogen-containing groups as astarting material.

[0047] As the compound having at least two active hydrogen-containinggroups, there can be cited dihydric alcohols such as ethylene glycol,diethylene glycol, propylene glycol, dipropylene glycol, neopentylglycol, 1,4-butanediol and 1,6-hexanediol; polyhydric alcohols having atleast three hydroxyl groups such as glycerol, trimethylolpropane,pentaerythritol, diglycerol, dextrose, sorbitol and sucrose; polyphenolssuch as resorcinol, hydroquinone and bisphenol A; polyamines such asethylenediamine, tolylenediamine, 1,3-propanediamine andisophoronediamine; alkanolamines such as diethanolamine andtriethanolamine; modified compounds thereof; and the like. These can beused alone or in admixture of at least two kinds.

[0048] The polyoxytetramethylene glycol can be prepared by ring-openingpolymerization of tetrahydrofuran.

[0049] As the polyol component, the above-mentioned polyester-polyolsand polyether-polyols can be used alone or in admixture of at least twokinds.

[0050] The number of the functional groups and the hydroxyl value of thepolyol component cannot be absolutely determined, because the number ofthe functional groups and the hydroxyl value differ depending upon thekinds of the desired polyurethane and required physical properties, andthe like. Therefore, it is desired that the number of the functionalgroups and the hydroxyl value are appropriately selected depending uponthe kinds of the desired polyurethane and required physical properties.Especially, when a rigid polyurethane foam is produced, it is preferablethat the number of the functional groups in the polyol component is 2 to8, and that its hydroxyl value is 250 to 700. Also, when a flexiblepolyurethane foam and a semi-rigid polyurethane foam are produced, it ispreferable that the number of the functional groups in the polyolcomponent is 2 to 4, and that its hydroxyl value is 10 to 200.

[0051] As the isocyanate component, there can be cited, for instance,aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, 4,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethanediisocyanate, 2,4′-diphenylmethane diisocyanate,polymethylenepolyphenylene polyisocyanate, xylylene diisocyanate andnaphthylene diisocyanate; aliphatic polyisocyanates such ashexamethylene diisocyanate and lysine diisocyanate; alicyclicpolyisocyanates such as hydrogenated diphenylmethane diisocyanate,hydrogenated tolylene diisocyanate and isophorone diisocyanate; modifiedcompounds of the above-mentioned polyisocyanates containing at least onebond such as urethane bond, carbodiimide bond, uretoimine bond,allophanate bond, urea bond, biuret bond and isocyanurate bond. Thesecan be used alone or in admixture of at least two kinds.

[0052] It is preferable that the proportion of the polyol component tothe isocyanate component is adjusted so that the isocyanate indexusually becomes 95 to 300. Also, it is especially preferable that theproportion of the polyol component to the isocyanate component isadjusted so that the isocyanate index becomes 95 to 120 with theexception of a particular case where the catalyst is used together witha catalyst for producing a polyisocyanurate.

[0053] The blowing agent used in the production of a polyurethane foamincludes water; low-boiling point hydrocarbons such as isopentane,normal pentane and cyclopentane; gases such as nitrogen gas, air andcarbon dioxide; HCFC-141b, HCFC-142b, HCFC-22, HFC-134a, HFC-152a,HFC-245fa, HFC-245ca, HFC-236ea, HFC-365mfc, and the like. These can beused alone or in admixture of at least two kinds.

[0054] The amount of the blowing agent cannot be absolutely determined,because the amount of the blowing agent differs depending upon its kindsand the density of the desired polyurethane foam. Therefore, it isdesired that the amount of the blowing agent is appropriately adjusteddepending upon the kinds of these blowing agents and the like.

[0055] When a polyurethane foam is produced, a surfactant can be used asoccasion demands. The surfactant may be any of those generally used inthe production of a polyurethane foam. As representative examples of thesurfactant, there can be cited silicone surfactants such asdimethylpolysiloxane and polyoxyalkylene-modified dimethylpolysiloxane;anionic surfactants such as salts of fatty acids, salts of sulfuric acidesters, salts of phosphoric acid esters and sulfonates; and the like.

[0056] The amount of the surfactant cannot be absolutely determined,because the amount of the surfactant differs depending upon its kindsand the density of the desired polyurethane foam. Therefore, it isdesired that the amount of the surfactant is appropriately adjusteddepending upon the kinds of these surfactants and the like.

[0057] Moreover, there can be employed optional components other thanthose mentioned above, for instance, other auxiliaries such ascross-linking agents, stabilizers, pigments, flame retardants andfillers within a range which would not hinder the object of the presentinvention.

[0058] The cross-linking agent includes low-molecular weight compoundshaving at least two active hydrogen-containing groups which are reactivewith hydroxyl group, primary amino group, secondary amino group, orother isocyanate groups. As its examples, there can be cited polyhydricalcohols such as ethylene glycol, diethylene glycol, propylene glycol,dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol,glycerol, trimethylolpropane, triethanolamine and alkylene oxide adductsof bisphenol A; polyamines such as diethyltoluenediamine,chlorodiaminobenzene, ethylenediamine and 1,6-hexanediamine; and thelike. These can be used alone or in admixture of at least two kinds.

[0059] As the stabilizer, there can be cited hindered phenolic radicalscavengers such as dibutylhydroxytoluene,pentaerythrityltetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]and isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; antioxidantssuch as phosphorous acid compounds such as phosphorous acid,triphenylphosphite, triethylphosphite and triphenylphosphine;ultraviolet absorbents such as 2-(5-methyl-2-hydroxyphenyl)benzotriazoleand a condensation product ofmethyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionatewith polyethylene glycol, and the like. These can be used alone or inadmixture of at least two kinds. Among these stabilizers, phosphorousacid compounds, especially triphenylphosphite andpentaerythrityltetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]can be suitably used from the viewpoint of improving the foam strength.Especially, when triphenylphosphite andpentaerythrityltetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]are used in combination, there is an advantage that the foam strengthcan be further enhanced.

[0060] As the pigment, there can be cited inorganic pigments representedby transition metal salts; organic pigments represented by azocompounds; carbon powder and the like. These pigments can be used aloneor in admixture of at least two kinds.

[0061] As the flame retardant, there can be cited halogen-based flameretardants such as tris(chloropropyl) phosphate.

[0062] As the filler, there can be cited inorganic compounds such assilica fine particles and alumina fine particles, and organic compoundssuch as melamine resins and phenolic resins.

[0063] A polyurethane foam can be formed by, for instance, mixing apolyol component with a blowing agent, the catalyst for producing apolyurethane, a surfactant and other auxiliaries to give a polyolmixture, mixing the resulting polyol mixture with an isocyanatecomponent with stirring with a blowing machine or the like, injectingthe mixture into a mold, and allowing the mixture to foam. Morespecifically, for example, the temperature of the above-mentioned polyolmixture is adjusted to 20° C. or so using a tank, and thereafter thepolyol mixture is reacted with the isocyanate component using a foamingmachine such as an automatically mixing and injecting foaming machine oran automatically blending and injecting foaming machine, whereby apolyurethane foam can be produced.

[0064] As explained above, since the catalyst used for producing apolyurethane of the present invention exhibits little odor, there areexhibited some excellent effects such that the catalyst is highlyexcellent in working surroundings during the production of thepolyurethane, and that odor based on the catalyst for producing apolyurethane is not generated from the polyurethane produced. Inaddition, when the catalyst for producing a polyurethane of the presentinvention is used, there can be produced a polyurethane excellent invinyl-staining resistance, fogging resistance and heat resistance.Therefore, the polyurethane produced by the process of the presentinvention can be suitably applied directly to the construction site as aheat insulating material for wall surface or ceiling of a house,building or the like. When the catalyst is used for producing asemi-rigid polyurethane foam, the obtained polyurethane can be suitablyused for automobile interior materials such as headrests and armrests.In addition, when the catalyst is used for producing a flexiblepolyurethane foam, since there is generated little odor due to thecatalyst, the obtained polyurethane can be suitably used forfurnishings, cushioning materials such as beddings, and interior seatcushioning materials for automobiles.

[0065] In addition, when the catalyst for producing a polyurethanecomprising the DAAA and the FTA compound is used, there can be rapidlyproduced a polyurethane foam with the generation of little odor based onthe catalyst for producing a polyurethane, and being excellent indimensional stability at low temperatures even in low-temperaturesurroundings as in winter season. Therefore, the process of the presentinvention using the catalyst for producing a polyurethane comprising theDAAA and the FTA compound can be especially suitably applied directly tothe construction site as a heat insulating material for wall surface orceiling of a house, building or the like when a heat insulating materialmade of a polyurethane foam is formed. Further, since little odor basedon the catalyst for producing a polyurethane are generated from theproduced polyurethane foam, the polyurethane foam can be suitably usedas cushioning materials such as headrests, and the like.

EXAMPLE 1 AND COMPARATIVE EXAMPLES 1 TO 4

[0066] 100 parts by weight of a branched polyether-polyol which is apolypropylene glycol prepared by adding ethylene oxide to the terminalof polypropylene glycol [manufactured by Sumitomo Bayer Urethane Co.,LTD. under the trade name of Sumiphen 3063, hydroxyl value: 28 mgKOH/g], 1.5 parts by weight of triethanolamine, 3.6 parts by weight ofwater as a blowing agent and a catalyst for producing a polyurethaneshown in Table 1 (the amount of the catalyst being adjusted so that thegelation time becomes equal in each Example and each ComparativeExample) were mixed with each other by a Labomixer to give a polyolmixture.

[0067] Next, the resulting polyol mixture and an isocyanate component[manufactured by Sumitomo-Bayer Urethane Co., LTD. under the trade nameof Sumidule 44V20] were mixed at 15° C. by a Labomixer with stirring, sothat the isocyanate index became 105. 250 g of the resulting mixture wasinjected into a mold [internal dimensions: 150 mm×150 mm×300 mm(height)], and a free foam of a semi-rigid polyurethane foam was molded.

[0068] The odor of the catalyst for producing a polyurethane, and asphysical properties of the polyurethane foam, the strength-retainingratio (heat resistance), the haze value (fogging resistance) and thefoam density of the core portion were evaluated on the bases of thefollowing methods. The results are shown in Table 1.

[0069] A. Odor of Catalyst for Producing Polyurethane

[0070] A 140 ml-glass bottle with a lid was charged with 2 g of acatalyst for producing a polyurethane foam, which was accuratelyweighed, used in each of Examples and Comparative Examples, and the lidwas placed on the bottle. The lidded bottle was allowed to stand in athermostatic chamber at 25° C. for 20 hours. Thereafter, odor wasdetermined with an odor sensor [manufactured by New Cosmos Electric Co.,Ltd., XP-329]. It is indicated in Table 1 that the smaller the numericalvalue is, the lower the odor is.

[0071] B. Strength-Retaining Ratio (Heat Resistance)

[0072] After the polyurethane foam was produced, the polyurethane foamwas allowed to stand at room temperature for 24 hours. Thereafter, inaccordance with JIS K 6301, 10 pieces of Type 2-dumbbell test pieces fordetermining tensile strength were cut out from the resultingpolyurethane foam, and 5 pieces of them were subjected to a test fordetermining tensile strength using a tensile tester [autographmanufactured by Shimadzu Corporation under the model number of DCS-50M]at a tensile speed of 125 mm/min at room temperature. The average of thetensile strength of the above 5 test pieces was calculated (initialstrength). Also, the remaining 5 test pieces were allowed to stand in anatmosphere having a temperature of 120° C. for 24 hours, and these testpieces were subjected to a test for determining tensile strength in thesame manner as described above. The average of the tensile strength ofthese test pieces was calculated (strength at high temperatures). Thestrength-retaining ratio was obtained from the equation:

[Strength-Retaining Ratio (%)]=[Strength at High Temperatures]÷[InitialStrength]×100,

[0073] and used as an index for heat resistance.

[0074] C. Haze Value (Fogging Resistance)

[0075] After the polyurethane foam was produced, the polyurethane foamwas allowed to stand at room temperature for 24 hours. Thereafter, atest piece (50 mm×50 mm×100 mm) was cut out from its core portion. Thetest piece was placed in a 500-ml glass bottle charged with 0.1 ml of 2N hydrochloric acid, and the opening of the bottle was tightly sealedwith a transparent glass plate. About two-third of the glass bottle wasdipped in a hot bath kept at 80° C. for 100 hours, and thereafter thehaze value of the glass plate was determined by using a haze meter(color difference meter) [manufactured by Nippon Denshoku Kogyo K.K.under the model number of NDH-20D], and used as an index for foggingresistance. It is indicated in Table 1 that the smaller the haze valueis, the lower the degree of fogging is.

[0076] D. Foam Density of Core Portion

[0077] After the free foam of a polyurethane foam was produced, the freefoam was allowed to stand for one day. Thereafter, a test piece having asize of 100 mm×100 mm×100 mm was cut out from its core portion. Theweight of the test piece was determined, and the foam density of thecore portion was calculated from the equation:

[Foam density of core portion]=[Weight of test piece]÷[Volume of testpiece] TABLE 1 Physical Properties of Polyurethane Foam Catalyst forProducing Foam Polyurethane Density Amount Strength- of Core Ex. (partsRetaining Haze Portion No. Kind by wt.) Odor Ratio Value (kg/m³) 15-Dimethyl-3- 3.5 128 80.2 0.2 53.5 methyl-1- pentanol Comp. 33.3% 3.4290 103.2 15.8 52.3 Ex. 1 Dipropylene Glycol Solution of Triethylene-diamine Comp. N,N,N',N' 2.4 380 102.2 36.0 53.6 Ex. 2 -tetramethyl-hexanediamine Comp. Trimethyl- 3.5 553 49.0 0.7 53.1 Ex. 3 aminopropyl-ethanolamine Comp. N,N-dimethyl- 4.5 1450 102.6 82.6 53.9 Ex. 4cyclohexyl- amine

[0078] It can be seen from the results shown in Table 1 that accordingto Example 1, the working environment during the production of thepolyurethane is improved since the catalyst for producing a polyurethanehas very weak odor. Also, it can be seen that the polyurethane foamobtained in Example 1 has a relatively high strength-retaining ratio,and fogging is less likely to be generated since its haze value is smallat high temperatures (80° C.).

[0079] A test for examining the vinyl-staining resistance was notcarried out. However, according to Example 1, since the DAAA is used asa catalyst for producing a polyurethane, and the DAAA has dimethylaminogroup and a primary hydroxyl group in its molecule and is incorporatedinto the polyurethane foam via chemical bond, the polyurethane foamexhibits the effects similar to the fogging resistance, namely the hazevalue as to the vinyl-staining resistance. Accordingly, it can be seenfrom the results of the haze value shown in Table 1 that thepolyurethane foam obtained in Example 1 is also excellent invinyl-staining resistance.

EXAMPLES 2 TO 8 AND COMPARATIVE EXAMPLES 5 TO 9

[0080] 100 parts by weight of a polyol component [45% by weight ofsucrose-based polyether-polyol (hydroxyl value: 380 mg KOH/g,manufactured by Sumitomo Bayer Urethane Co., LTD. under the trade nameof Polyol 1703); 45% by weight of tolylenediamine-based polyether-polyol(hydroxyl value: 450 mg KOH/g, manufactured by Asahi Glass Company Ltd.under the trade name of Excenol 455AR); and 10% by weight ofglycerol-based polyether-polyol (hydroxyl value: 235 mg KOH/g,manufactured by MITSUI CHEMICALS, INC. under the trade name of PolyolMN-700)], 1.5 parts by weight of a surfactant [manufactured by NipponUnicar Company Limited under the trade name of L-5340: silicone-basedsurfactant], 0.5 parts by weight of water and 27.5 parts by weight ofHCFC-141b as blowing agents, and a catalyst for producing a polyurethaneshown in Table 2 were mixed in a Labomixer, to give a mixture (polyolmixture).

[0081] Next, the resulting polyol mixture was mixed with an isocyanatecomponent [manufactured by Sumitomo-Bayer Urethane Co., LTD. under thetrade name of Sumidule 44V20] at 5° C. by a Labomixer with stirring, sothat the isocyanate index became 105. 250 g of the resulting mixture wasinjected into a mold [internal dimensions: 150×150×300 (height) mm], anda free foam of a rigid polyurethane foam was molded.

[0082] The foam density of the core portion of the obtained rigidpolyurethane foam and the odor of the catalyst for producing apolyurethane were evaluated in the same manner as in Example 1. Thereactivity during the production of the rigid polyurethane foam, and thedimensional stability (low-temperature shrinkage ratio) at lowtemperatures of the rigid polyurethane foam were evaluated on the basesof the following methods. The results are shown in Table 2.

[0083] E. Reactivity

[0084] 40 g of the mixture of the polyol mixture and the isocyanatecomponent, obtained in each of Examples and Comparative Examples waspoured into a 300 ml-plastic cup, and the time period for reaching creamtime (hereinafter referred to as CT) and the time period for reachingthe gel time (hereinafter referred to as GT) during free foaming weredetermined.

[0085] F. Dimensional Stability at Low Temperatures

[0086] The test piece which was prepared when evaluating the foamdensity of the core portion was placed in a thermostatic chamber at −5°C., and allowed to stand for 24 hours. Thereafter, as shown in FIG. 1,the dimensional stability in the direction perpendicular to the foamingdirection of a test piece 1 was obtained from the equation:

[Dimensional Stability (%)]=[Dimension after allowing to stand−Dimensionbefore allowing to stand]÷[Dimension before allowing to stand]×100 TABLE2 Foam Re- Density activity of Core Dimensional Components of Catalystfor Producing Polyurethane (sec) Portion Stability Ex. No. (parts byweight) CT GT (kg/m³) (%) Odor 2 DMAMP (1.0) 3-Dimethylaminopropylamine(3.0) 13 47 30.9 −2.2 724 3 DMAMP (2.0) 3-Dimethylaminopropylamine (2.0)15 48 30.7 −2.9 262 4 DMAMP (3.0) 3-Dimethylaminopropylamine (1.0) 16 4930.6 −3.3 161 5 DMAMP (0.5) 3-Dimethylaminopropylamine (3.5) 12 46 31.2−2.0 820 6 DMAMP (2.0) 4-Dimethylaminobutylamine (2.0) 15 48 31.2 −2.6343 7 DMAMP (2.0) 6-Dimethylaminohexylamine (2.0) 16 49 31.1 −2.8 307 8DMAMP (2.0) 3-(2-Dimethylaminoethoxy)- (2.0) 16 49 30.5 −3.9 290propylamine Comp. DMAMP (4.0) — 18 53 31.0 −7.7 128 Ex. 5 Comp. —3-Dimethylaminopropylamine (4.0) 12 45 30.7 −2.1 2000< Ex. 6 Comp. —4-Dimethylaminobutylamine (4.0) 12 46 30.6 −3.0 2000< Ex. 7 Comp. —6-Dimethylaminohexylamine (4.0) 13 47 30.3 −2.8 2000< Ex. 8 Comp. —3-(2-Dimethylaminoethoxy)- (4.0) 13 47 30.1 −3.1 2000< Ex. 9 propylamine

[0087] It can be seen from the results shown in Table 2 that accordingto Examples 2 to 8, the reactivity during the production of thepolyurethane foam is excellent since CT and GT are short periods of timenevertheless the molding is carried out at low temperatures, and thedimension stability at low temperatures is excellent since there islittle change in dimensions. Also, it can be seen that there can beobtained polyurethane foams generating little odor based on the catalystfor producing a polyurethane since a catalyst having dimethylamino groupand a primary amino group or hydroxyl group in its molecule is used andthe catalyst itself is non-transferable from the polyurethane foam.

INDUSTRIAL APPLICABILITY

[0088] When the catalyst for producing a polyurethane comprising theDAAA is used, there can be produced a polyurethane having little odorand being excellent in vinyl-staining property, fogging resistance andheat resistance. In addition, when the catalyst for producing apolyurethane comprising the DAAA and the FTA is used, there can berapidly produced a polyurethane foam excellent in dimensional stabilityeven in low-temperature surroundings with generating little odor duringthe production of the polyurethane foam.

1. A catalyst for producing a polyurethane, comprising adialkylaminoalkyl alcohol represented by the formula (I):R¹R²N—X—OH  (I) wherein each of R¹ and R² is independently an alkylgroup having 1 to 4 carbon atoms; and X is a branched alkylene grouphaving 4 to 8 carbon atoms.
 2. The catalyst for producing a polyurethaneaccording to claim 1, wherein the compound represented by the formula(I) is 5-dimethylamino-3-methyl-1-pentanol.
 3. A process for producing apolyurethane, comprising reacting a polyol component with an isocyanatecomponent in the presence of a catalyst for producing a polyurethanecomprising a dialkylaminoalkyl alcohol represented by the formula (I):R¹R²N—X—OH  (I) wherein each of R¹ and R² is independently an alkylgroup having 1 to 4 carbon atoms; and X is a branched alkylene grouphaving 4 to 8 carbon atoms.
 4. The process for producing a polyurethanefoam according to claim 3, wherein the polyol component is reacted withthe isocyanate component in the presence of a catalyst for producing apolyurethane, comprising a dialkylaminoalkyl alcohol represented by theformula (I), and a blowing agent.
 5. The process according to claim 3 or4, wherein the dialkylaminoalkyl alcohol represented by the formula (I)is 5-dimethylamino-3-methyl-1-pentanol.
 6. A process for producing apolyurethane foam, comprising reacting a polyol component with anisocyanate component in the presence of a catalyst for producing apolyurethane, comprising a dialkylaminoalkyl alcohol represented by theformula (I): R¹R²N—X—OH  (I) wherein each of R¹ and R² is independentlyan alkyl group having 1 to 4 carbon atoms; and X is a branched alkylenegroup having 4 to 8 carbon atoms, and a compound having a primary aminogroup and a tertiary amino group in its molecule, and a blowing agent.7. The process according to claim 6, wherein the dialkylaminoalkylalcohol represented by the formula (I) is5-dimethylamino-3-methyl-1-pentanol.
 8. The process according to claim 6or 7, wherein the compound having a primary amino group and a tertiaryamino group in its molecule is represented by the formula (II):R³R⁴N—(CH₂)_(m)—A—(CH₂)_(n)—NH₂  (II) wherein each of R³ and R⁴ isindependently an alkyl group having 1 to 4 carbon atoms, or may bebonded to each other to form a 3- to 6-membered nitrogen atom-containingheterocyclic group; A is oxygen atom or a single bond, and when A isoxygen atom, each of m and n is independently an integer of 2 to 6, andwhen A is a single bond, each of m and n is an integer satisfying m+n=2to
 8. 9. The process according to any one of claims 6 to 8, wherein thecompound having a primary amino group and a tertiary amino group in itsmolecule is at least one compound selected from the group consisting of3-dimethylaminopropylamine, 4-dimethylaminobutylamine,6-dimethylaminohexylamine and 3-(2-dimethylaminoethoxy)propylamine. 10.The process according to any one of claims 6 to 9, wherein thedialkylaminoalkyl alcohol represented by the formula (I)/the compoundhaving a primary amino group and a tertiary amino group in its molecule[weight ratio] is 5/95 to 95/5.